1. Field of the Invention
The present invention relates to processing an audio signal in order to enhance the sound output.
2. Description of the Related Art
In loudspeaker designs, the ability of the woofer to produce low frequencies is dictated by its size and power. With the increasing drive towards Small speaker designs, the bass cut-off frequency of such loudspeaker systems becomes higher. The missing fundamental effect is known. The brain perceives the pitch of a tone by the ratio of higher harmonics related to a fundamental, and not just by the fundamental itself. Thus, if the ear detects a series of harmonic frequencies not containing the fundamental frequency itself, the brain will still perceive the fundamental frequency to be present. Generating higher harmonics above the bass cut-off frequency of a loudspeaker when polyphonic sound is being played is difficult. A technique is therefore required to pitch shift the audio by one octave, thereby producing a first harmonic, and then produce additional higher-order harmonics.